Chair back



FIG. 1 is a perspective view of a chair back showing my new design, it being understood that the broken lines are for illustrative purposes only and form no part of the claimed design;

FIG. 2 is an enlarged front elevational view thereof;

FIG. 3 is a side elevational view of FIG. 2, it being understood that the opposite side is a mirror image thereof;

FIG. 4 is top plan view of FIG. 2;

FIG. 5 is a bottom plan view of FIG. 2;

FIG. 6 is a rear elevational view of FIG. 2;

FIG. 7 is a perspective view of a chair back showing a second embodiment of my new design, it being understood that the broken lines are for illustrative purposes only and form no part of the claimed design;

FIG. 8 is an enlarged front elevational view thereof;

FIG. 9 is a side elevational view of FIG. 8, it being understood that the opposite side is a mirror image thereof;

FIG. 10 is a top plan view of FIG. 8;

FIG. 11 is a bottom plan view of FIG. 8; and,

FIG. 12 is a rear elevational view of FIG. 8. 

The ornamental design for a chair back, as shown and described. 